Sediment Yield Calculation Along the Red Sea Coastal Drainage Basins

Abstract

Sediment yield rate calculation formulations are lacking in arid regions, because almost all the studies are concerned with humid environments. Although drainage basins (wadis) in arid regions are studied from different points of view, unfortunately there has been insufficient work on the possible sediment yield and transportation. Sediment yield within a drainage basin is a combined consequence of upland, gully, and channel erosion, transportation, and depositional processes. In arid zones, although wind deposition plays a significant role, occasional floods and flash floods are the main causes along the main channel. In fact, the bulk of the sediment yield is due to surface water runoff after each storm rainfall. This paper provides an efficient application of some available sediment yield formulations for arid regions by considering drainage basin morphology, and runoff discharge calculated for a 100-year return period. Morphological variables include the drainage basin area, drainage basin slope, main channel slope and the drainage density. This paper, after the presentation of brief information about the sediment yield process in arid regions, suggests the application of some formulas developed for arid region sediment calculation to three watersheds along the Red Sea coastal area within the Kingdom of Saudi Arabia. Two different sediment yield formulations are employed, where the first includes the drainage area, slope and the flood discharge, and the other includes additionally the drainage density. These wadis (drainage basins) from the north to the south are Al-Amud, Masturah and Yabah. According to the second formulation it is calculated that for a 100-year return period sediment rates are 0.00048 m3/s, 0.02165 m3/s and 0.03064 m3/s, respectively.